6,245 research outputs found
Rapidity bin multiplicity correlations from a multi-phase transport model
The central-arbitrary bin and forward-backward bin multiplicity correlation
patterns for Au+Au collisions at = GeV are
investigated within a multi-phase transport (AMPT) model. An interesting
observation is that for GeV Au+Au collisions, these two
correlation patterns both have an increase with the pseudorapidity gap, while
for GeV Au+Au collisions, they decrease. We mainly
discuss the influence of different evolution stages of collision system on the
central-arbitrary bin correlations, such as the initial conditions, partonic
scatterings, hadronization scheme and hadronic scatterings. Our results show
that the central-arbitrary bin multiplicity correlations have different
responses to partonic phase and hadronic phase, which can be suggested as a
good probe to explore the dynamical evolution mechanism of the hot dense matter
in high-energy heavy-ion collisions.Comment: 7pages, 6 figures, accepted for publication in EPJ
Identification and characterization of neurofibromatosis type 1 (NF1) gene mutations
La neurofibromatose 1 (NF 1) affecte un individu sur 3000 et se caractĂ©rise par l'extrĂȘme variabilitĂ© des symptĂŽme cliniques. Le gĂšne de NF/, situĂ© sur le chromosome l 7q 11.2, contient 350 kb et 60 exons. Le taux de mutation est de 1 x 104/gamĂšte/gĂ©nĂ©ration. Environ 50% des mutations sont d'origine familiale et 50% sporadique. Nous avons identifiĂ© et caractĂ©risĂ© une mutation qui cause l'exclusion des exons 11 et l 2a, six dĂ©lĂ©tions et un polymorphisme HinclI et aussi dĂ©terminĂ© le dĂ©sĂ©quilibre de liaison dans la population quĂ©bĂ©coise. Une mutation originale a Ă©tĂ© identifiĂ©e grĂące au test de tronquation des protĂ©ines; elle serait la cause de l'exclusion d'exons. Le sĂ©quençage de la rĂ©gion gĂ©nomique entre les introns 1 Oc et 12a a permis d'identifier le changement d'un G en A en position 2056+ l dans le site d' Ă©pissage 5' de l 'exon 12a. Ceci engendre l'excision des deux exons l l et 12a sans changement du cadre de lecture et sans que la quantitĂ© des ARN messagers en soit affectĂ©e. Des essais d'Ă©pissage in vivo et in vitro nous ont permis de dĂ©montrer pour la premiĂšre fois que le mutation naturelle supprime la dĂ©finition des exons. Nos rĂ©sultats montrent aussi que la sĂ©quence encodĂ©e par les exons 11 et l 2a est essentielle pour l'activitĂ© de la neurofibromine. L 'haplotypage de 19 familles a permis de dĂ©tecter la perte d'hĂ©tĂ©rozygositĂ© (LOH) grĂące aux 4 microsatellites et aux RFLPs RsaI et EcoRI. Six dĂ©lĂ©tions (2 familles:76 l 0 et 74 73, et 4 patients: 178, 184, 236 et 23 7) ont Ă©tĂ© identifiĂ©es et caractĂ©risĂ©es par la LOH et des buvardages de type Southern. La dĂ©lĂ©tion dans la famille 7610 est d'origine maternelle et seul restent les exons l-4b. La dĂ©lĂ©tion dans la famille 7473 est aussi d'origine maternelle et les exons de lĂ 5 sont dĂ©lĂ©tĂ©s, la dĂ©lĂ©tion s'arrĂȘtant quelque part avant l' intron 26. Avec le patient 1 78 la dĂ©lĂ©tion commence entre les exons 23-2 et 27b pour se terminer aprĂšs la rĂ©gion 3' de NFJ. La dĂ©lĂ©tion dans le patient 184 commence au 5' du gĂšne et se termine entre les exons 27b-29. La dĂ©lĂ©tion dans le patient 236 commence entre les exons 14-18 et se termine aprĂšs l'extrĂ©mitĂ© 3' de NFJ. Avec le patient 237, la dĂ©lĂ©tion commence entre les exons 38-45 et se termine aprĂšs la rĂ©gion 3' du gĂšne. Ces dĂ©lĂ©tions sont distribuĂ©es au hasard dans le gĂšne NF 1.Abstract: Neurofibromatosis type 1 (NF1) afflicts 1 in 3,000 individuals and is characterized with variable clinical presentations. The NF1 gene spans 350 kb on chromosome 17q11.2 with 60 exons. The gene exhibits high mutation rate of 1 Ă 104/gamete/generation and approximately 50% are sporadic new mutations. In this study, a splice site mutation and 6 gross deletions have been identified and characterized. Also, a HincII polymorphism was detected and the linkage disequilibrium was investigated. Using a protein truncation assay, we have identified a exon skipping mutation. The mutation, which consists of a G to A transition at position +1 (2056+1) of the 5' splice site of exon 12a, is associated with the loss of both exons 11 and 12a in the NF1 mRNA. The mutation inactivates the 5' splice site of exon 12a, prevents exon definition and leads to the skipping of both exons 11 and 12a. These results document the first example of a natural mutation that inactivates exon definition, and suggest that the 11-12a region of NF1 plays an important role in the activity of neurofibromin. Six gross deletions (families 7610 and 7473, patients 178, 184, 236 and 236) have been identified. The breakpoint of the deletion is located between exons 5 and 26. The deletions are unique and different from those reported previously. The deletions are not associated with unusual clinical features. The HincII polymorphism is located between exons 1 and 4a as defined by probe GE2-400 bp. Three alleles are detected: A1 (3.1 and 3.3 kb), A2 (2.4 and 4.0 kb), A3 (1.3 and 5.1 kb). The detected heterozygote forms are A1-A2, or A1-A3 and the homozygote forms A1-A1 or A2-A2. Analysis haplotypes of the 19 NF1 families indicates that the four intragenic polymorphic microsatellites are strongly linked with the NF1 disease. However, no linkage disequilibrium and founder effect was observed in this QuĂ©bec population collection. In conclusion, the study shows that the analysis of NF1 gene mutation is complex. No particular founder mutation has been observed in the QuĂ©bec population."--RĂ©sumĂ© abrĂ©gĂ© par UM
Antecedents driving the different levels of behavioral engagement in online travel communities
With the rapid development of online travel communities, understanding the determinants of users â engagement with the online travel communities is critically important for researchers and practitioners. The purpose of this study is to understand which environmental cues drive the engagement behaviors. Specifically, by using a rich data set from a large travel knowledge sharing website and seemingly unrelated regression model, we investigate and compare the antecedents leading to two different behavioral engagements including liking and social interaction. We find that information-, source-, and social interaction-level cues are associated with these behavioral engagements. The results also demonstrate the differential effectiveness of these cues between these two engagement behaviors. Our empirical findings provide theoretical and practical implication for online travel community operators to build a vibrant and successful online travel community
Trace initial interaction from final state observable in relativistic heavy ion collisions
In order to trace the initial interaction in ultra-relativistic heavy ion
collision in all azimuthal directions, two azimuthal multiplicity-correlation
patterns -- neighboring and fixed-to-arbitrary angular-bin correlation patterns
-- are suggested. From the simulation of Au + Au collisions at 200 GeV by using
the Monte Carlo models RQMD with hadron re-scattering and AMPT with and without
string melting, we observe that the correlation patterns change gradually from
out-of-plane preferential one to in-plane preferential one when the centrality
of collision shifts from central to peripheral, meanwhile the anisotropic
collective flow v_2 keeps positive in all cases. This regularity is found to be
model and collision energy independent. The physics behind the two opposite
trends of correlation patterns, in particular, the presence of out-of-plane
correlation patterns at RHIC energy, are discussed.Comment: 5pages, 4figure
Self-templating and in situ assembly of a cubic cluster-of-clusters architecture based on a {Mo24Fe12} inorganic macrocycle
Engineering self-templating inorganic architectures is critical for the development of bottom-up approaches to nanoscience, but systems with a hierarchy of templates are elusive. Herein we describe that the cluster-anion-templated (CAT) assembly of a {CAT}â{Mo24Fe12} macrocycle forms a giant ca. 220â
nm3 unit cell containing 16â
macrocycles clustered into eight face-shared tetrahedral cluster-of-clusters assemblies. We show that {CAT}â{Mo24Fe12} with different CATs gives the compounds 1â4 for CAT=Anderson {FeMo6} (1), Keggin {PMo12} (2), Dawson {P2W18} (3), and {Mo12O36(HPO3)2} (4) polyoxometalates. âTemplate-freeâ assembly can be achieved, whereby the macrocycle components can also form a template inâ
situ allowing template to macrocycle to superstructure formation and the ability to exchange the templates. Furthermore, the transformation of template clusters within the inorganic macrocycle {Mo24Fe12} allows the self-generation of an uncapped {Mo12O36(HPO3)2} in compound 4
TriaquaÂ(2,2âČ-bipyridine N,NâČ-dioxide-Îș2 O,OâČ)(5-nitroÂbenzene-1,3-dicarboxylÂato-ÎșO 1)zinc(II)
In the title compound, [Zn(C8H3NO6)(C10H8N2O2)(H2O)3], the ZnII ion is coordinated in a distorted octaÂhedral geometry by three water molÂecules, one O atom from a 5-nitroÂbenzene-1,3-dicarboxylÂate ligand and two O atoms from a chelating 2,2âČ-bipyridine N,NâČ-dioxide ligand. An extensive network of OâHâŻO hydrogen bonds is formed between the water molÂecules and the carboxylÂate groups. CâHâŻO interÂactions are also present
On a heuristic point of view concerning the optical activity
Motivated by a recent finding that Fresnel's phenomenological description of
the optical activity in the chiral medium is not self-consistent, we conduct a
thorough investigation into the nature of the polarization of a plane light
wave. We demonstrate that the polarization of light is the reflection of one of
its quantum-mechanical properties, called the quasi-spin. Unexpectedly, the
quasi-spin is not an observable with respect to the laboratory coordinate
system. Instead, it is with respect to the momentum-dependent local coordinate
system. The representative operators for the quasi-spin are the Pauli matrices.
The wavefunction is the Jones vector. In order to completely determine a state
of polarization, two different kinds of degrees of freedom are needed. One is
the degrees of freedom to characterize the state of quasi-spin. They are the
Stokes parameters, the expectation values of the Pauli matrices in the state
described by the Jones vector. The other is the degrees of freedom to specify
the local coordinate system, including the propagation direction and an angle
of rotation about it. Accordingly, there are two independent mechanisms to
change the state of polarization. One is to change the state of quasi-spin in a
fixed local coordinate system. This is the traditional mechanism that can be
expressed as an SU(2) rotation of the Jones vector. The other is to change the
local coordinate system with the state of quasi-spin remaining fixed in it. At
last, we show that it is the newly-identified mechanism that accounts for the
optical activity.Comment: 24 page
Stokes parameters alone cannot completely characterize the polarization of plane light waves
It was generally assumed that the Stokes parameters are complete
characterization for the state of polarization of a plane light wave so that
their counterparts in quantum optics, called the Stokes operators, represent
the polarization of photons. Here we show, through analyzing the properties of
polarized plane waves in an optically active medium, that the Stokes parameters
are not able to completely characterize the state of polarization of a plane
wave. The key point is that only when a plane wave is expanded in terms of the
orthogonal base modes, which are physically meaningful, can the two expansion
coefficients make up the Jones vector. Taking this into consideration, we
demonstrate that the Stokes parameters of any elliptically polarized wave in an
isotropic chiral medium, determined solely by its Jones vector, are transmitted
unchanged. They are not able to reflect the rotation of its polarization
ellipse along with the propagation. The relationship of the Stokes parameters
with the polarization of light needs further investigation.Comment: 13 page
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